164 THE ARCTOG^EIC REALM. [CHAP. 



The Tragulidce, or chevrotains, which form a group distinct 

 both from the cameloids and the true ruminants, are now confined 

 to the Oriental and Ethiopian regions, being represented in the 

 former area by the true chevrotains (Tragulus), and in the latter 

 by the single existing species of water-chevrotain (Dorcatheriuni). 

 Representatives of the latter genus occur, however, in the Miocene 

 and Pliocene strata of Europe ; while in the Oligocene we meet 

 with the more generalised extinct genera Prodremotherium and 

 Bachitheriuwi. In North America the group is but poorly repre- 

 sented, and apparently confined to the White River Oligocene, 

 where we find two types described under the names of Leptomeryx 

 and Hypertragulus ; the latter differing from the existing forms by 

 having both the third and fourth metacarpals and the correspond- 

 ing metatarsals separate, instead of being fused together to form a 

 cannon-bone. It is difficult to decide whether the group was 

 originally an Old or a New World one ; but, on the whole, it is 

 probable that it originated in the former area. 



We now come to the true ruminants, or Pecora, forming the 

 most specialised group of all the artiodactyle section of the ungu- 

 lates, and characterised by the completely crescentic, or selenodont 

 conformation of the columns of their molar teeth, which are 

 frequently of great height ; and likewise by the fusion of the third 

 and fourth metacarpals and metatarsals into a cannon-bone, and 

 by the imperfect development or disappearance of the lateral 

 metacarpals and metatarsals. In the family of the Cervida the 

 typical deer, or those included in the genus Cervus, are almost 

 exclusively Arctogseic 1 , being found in all the regions of the realm, 

 except the Sonoran, Ethiopian, and Malagasy. The reindeer 

 (Rangifer] and elk (Alces] are also solely Arctogseic forms, but 

 have a more restricted range, being confined to the more northern 

 portions of the Holarctic region. A more striking case is afforded 

 by the hollow-horned ruminants, or Bovidce, the whole of the 

 numerous members of which are confined to the realm under con- 

 sideration, with the sole exception of the anoa (Bos depressicornis] 

 of Celebes ; and even the latter, as we have seen in an earlier 

 chapter, is very closely related to certain extinct Indian forms. It 



1 The only exception is Cervus timoriensis, which may have been introduced 

 into its present habitat. 



